This invention relates to a new and improved tamperresistant container neck construction.
1. Field of Invention
The present invention relates to a plastic bottle neck preferably of a blow-molded, thin-walled type used to package milk, water and other liquid, particularly in retail stores. Such containers have been manufactured with increasingly thinner walls. The thinner the wall, the more prone the neck is to deformation. A plastic bottle cap fits over the neck and engages therewith by means of beads on the interior of the skirt of the cap engaging in grooves in exterior wall of the neck or other means. When the cap is intact, the closure of the cap and neck is said to be "tamper-resistant" in the sense that the skirt of the cap must be at least partially torn away in order to remove the cap and provide access to the contents of the container. When the container neck is made very thin the possibility of prying the cap off the neck because the thin-walled neck is subject to deformation, has become a problem. The present invention inhibits dishonest persons from removing the cap without tearing the skirt thereof.
Another problem arising from the use of thin-walled necks occurs when the cap is applied to the container at the bottling works. Downward pressure is applied to the cap, causing the cap and neck to deform to permit the beads of the cap to snap over the neck and engage in the grooves thereof. The present invention provides a deformable outward bulging "bumper" ring below the neck which is interrupted by straight-walled sections which prevents collapse of the neck when the cap is applied.
Although especially intended for use in thin-walled containers, the invention has utility in thicker bottles.
2. Description of the Prior Art
The cap of the present invention is subject to considerable variation. One preferred cap form with which the neck construction is usable is shown in U.S. Pat. No. 4,202,455. The cap shown in that patent is an improvement upon an earlier U.S. Pat. No. 3,338,446. The caps function in that they have a top disc from which depend an inner skirt which fits within and seals against the inside of the container neck and an outer skirt which fits around the container neck. The outer skirt has internal beads which fit into the grooves in the exterior of the neck. Such beads may be continuous or interrupted. The outer skirt also has a circumferential scoreline intermediate the beads and a second scoreline extending down from the first mentioned scoreline to the bottom edge of the skirt. A tear tab on the bottom edge of the skirt may be gripped by the user and torn upward, causing the cap to tear along the second scoreline and thence around circumferential scoreline. Such tearing of the skirt removes one of the two beads which hold the cap in place. With only one bead remaining, the upper portion of the cap becomes a reclosure cap which may be repeatedly pried off the neck and replaced until the container is discarded.
The present invention is used with a typical cap of this type and variations thereof.
To prevent dishonest patrons prying the cap off by inserting the fingernails under the bottom edge of the cap, a horizontal shoulder has been formed on necks immediately below the bottom edge of the skirt, as shwon for example in U.S. Pat. No. 4,438,857. The present invention comprises an improvement upon such structure.